U.S. patent application number 17/405758 was filed with the patent office on 2022-04-07 for elevator systems.
The applicant listed for this patent is Otis Elevator Company. Invention is credited to Felix Benjamin Donath, Jan Ruhnke.
Application Number | 20220106153 17/405758 |
Document ID | / |
Family ID | 1000005835838 |
Filed Date | 2022-04-07 |
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United States Patent
Application |
20220106153 |
Kind Code |
A1 |
Ruhnke; Jan ; et
al. |
April 7, 2022 |
ELEVATOR SYSTEMS
Abstract
An elevator system (201) includes an elevator car (203), a
controller (215), a position reference system (234; 213) configured
to provide a position of the elevator car (203) and at least one
safety device (230) configured to indicate a potential hazard
within the elevator system (201). When the actual position of the
elevator car (203) cannot be determined using the position
reference system (234), the controller (215) is configured to
calculate at least one potential position of the elevator car (203)
based on an assumed motion profile (237). The controller is
configured to allow the elevator car (203) to move whilst no safety
device (230), which corresponds to the at least one potential
position of elevator car (203) is triggered and to stop movement of
the elevator car (203) when a safety device (230) which corresponds
to the at least one potential position of the elevator car is
triggered.
Inventors: |
Ruhnke; Jan; (Berlin,
DE) ; Donath; Felix Benjamin; (Berlin, DE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Otis Elevator Company |
Farmington |
CT |
US |
|
|
Family ID: |
1000005835838 |
Appl. No.: |
17/405758 |
Filed: |
August 18, 2021 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B66B 1/3492 20130101;
B66B 3/002 20130101; B66B 1/24 20130101; B66B 5/02 20130101 |
International
Class: |
B66B 1/24 20060101
B66B001/24; B66B 1/34 20060101 B66B001/34; B66B 3/00 20060101
B66B003/00; B66B 5/02 20060101 B66B005/02 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 2, 2020 |
EP |
20199901.8 |
Claims
1. An elevator system (201) comprising: an elevator car (203)
arranged within an elevator shaft (217); a controller (215)
configured to control movement of the elevator car (203); a
position reference system (234; 213) configured to provide a
position of the elevator car (203) within the elevator shaft; and
at least one safety device (230) configured to indicate, when
triggered, a potential hazard within the elevator system (201);
wherein when an actual position of the elevator car (203) cannot be
determined using the position reference system (234; 213), the
controller (215) is configured to: calculate at least one potential
position (248) of the elevator car (203) based on an assumed motion
profile (237) of the elevator car (203); and allow the elevator car
(203) to move whilst no safety device (230), which corresponds to a
potential position (248) of elevator car (203) is triggered; and
stop movement of the elevator car (203) when a safety device (230)
which corresponds to a potential position of the elevator car is
triggered.
2. An elevator system (201) as claimed in claim 1, wherein the
assumed motion profile (237) comprises an elevator car speed
component (239) which comprises a maximum possible speed of the
elevator car (203).
3. An elevator system (201) as claimed in claim 1, wherein the
motion profile (237) comprises a direction of travel (241)
component of the elevator car (203).
4. An elevator system (201) as claimed in claim 1, wherein the at
least one potential position (248) of the elevator car (203)
comprises a plurality of potential positions (248).
5. An elevator system as claimed in claim 1, wherein calculating
the at least one potential position comprises calculating the at
least one potential position periodically.
6. An elevator system (201) as claimed in claim 1, wherein each of
the at least one potential position (248) corresponds to at least
one positional zone within the elevator shaft (217).
7. An elevator system (201) as claimed in claim 1, wherein the
position reference system (234; 213) comprises an absolute position
reference system (234) configured to provide an absolute position
of the elevator car (203) within the elevator shaft (217).
8. An elevator system (201) as claimed in claim 1, wherein the at
least one safety device (230) comprises a plurality of safety
devices.
9. A method of controlling the operation of an elevator car (203)
within an elevator shaft (217) comprising a plurality of safety
devices (230) configured to indicate a hazard in the elevator
system (201), the method comprising: monitoring a position of the
elevator car (203) using a position reference system (234; 213);
when an actual position of the elevator car (203) cannot be
determined from the position reference system (234; 213),
calculating at least one potential position (248) of the elevator
car (203) based on an assumed motion profile (237) of the elevator
car (203); and allowing the elevator car (203) to move when no
safety device (230) is triggered which corresponds to a potential
position (248) of the elevator car (203), and stopping the elevator
car (203) from moving when a safety device (230) is triggered which
corresponds to a potential position (248) of the elevator car
(203).
10. A method as claimed in claim 9, wherein the assumed motion
profile (237) comprises an elevator car speed (239) comprising a
maximum possible speed of the elevator car (203).
11. A method as claimed in claim 9, wherein the assumed motion
profile (237) comprises a direction of movement component
(241).
12. A method as claimed in claim 9, wherein calculating the at
least one potential position (248) comprises calculating a
plurality of potential positions (248).
13. A method as claimed in claim 9, wherein the at least one
potential position (248) corresponds to positional zones (248)
within the elevator shaft (217).
14. A computer program product comprising computer-executable
instructions which, when read by a machine, cause the machine to
perform the method according to claim 9.
15. A computer readable medium having the computer program product
of claim 14 stored therein.
Description
FOREIGN PRIORITY
[0001] This application claims priority to European Patent
Application No. 20199901.8, filed Oct. 2, 2020, and all the
benefits accruing therefrom under 35 U.S.C. .sctn. 119, the
contents of which in its entirety are herein incorporated by
reference.
TECHNICAL FIELD
[0002] This disclosure relates to elevator systems and methods, for
example to elevator systems and methods for operating an elevator
car when the position of the elevator car cannot accurately be
determined.
BACKGROUND ART
[0003] Elevator systems comprising an elevator car typically rely
upon accurate information regarding the position of the elevator
car within the elevator shaft, in which it travels. Accurate
positional information allows the system to control movement of the
elevator car and stop the elevator car at appropriate positions in
the elevator shaft, e.g. at elevator landings. Knowledge of the
precise position of the elevator car is also important so that the
system can quickly stop the elevator car in emergencies, e.g.
following the triggering of an emergency sensor.
[0004] In certain instances, it may not be possible to accurately
determine the position of the elevator car within the elevator
shaft. For example, elevator shafts can become relatively dirty due
to the generation of dust from the mechanical components within the
elevator shaft. Dirt, e.g. dust, within the elevator system can
make it difficult to accurately determine the position of the
elevator car. For example, in systems which comprise a position
reference system, e.g. an optical position reference system, dirt
on the position reference system may prevent it from being able to
accurately indicate the elevator car's position.
[0005] In prior art systems, as soon as the position of the
elevator car can no longer accurately be determined, the system
immediately assumes a worst case scenario and operates on the basis
that the elevator car could be anywhere within the entire elevator
shaft. In systems which comprise virtual limit switches, this worst
case scenario typically causes the triggering of the virtual limit
switches, e.g. an upper or lower virtual limit switch, which
results in the immediate stopping of the elevator car. Whilst this
may help to ensure the safety of any passengers within the elevator
car, this immediate stopping of the elevator car can be a nuisance
for passengers as the elevator car may be stopped between two
landings, thus resulting in the passengers becoming trapped in the
elevator car.
[0006] It would be advantageous to provide an elevator system which
addresses the problems outlined above.
SUMMARY OF THE DISCLOSURE
[0007] In accordance with a first aspect, the present disclosure
provides an elevator system comprising: an elevator car arranged
within an elevator shaft; a controller configured to control
movement of the elevator car; a position reference system
configured to provide a position of the elevator car within the
elevator shaft; and at least one safety device configured to
indicate, when triggered, a potential hazard within the elevator
system; wherein when an actual position of the elevator car cannot
be determined using the position reference system, the controller
is configured to: calculate at least one potential position of the
elevator car based on an assumed motion profile of the elevator
car; allow the elevator car to move whilst no safety device which
corresponds to a potential position of elevator car is triggered;
and stop movement of the elevator car when a safety device which
corresponds to a potential position of the elevator car is
triggered.
[0008] Thus it will be appreciated that aspects of the present
disclosure provide an improved elevator system in which the
elevator car may be allowed to continue to move within the elevator
shaft, even in the event of a loss of actual, i.e. accurate,
positional information. The elevator car may be allowed to move at
least until a safety device is triggered which corresponds to a
potential position of the elevator car. Of course, if the elevator
is stationary at the time that the accurate position of the
elevator car is lost, the elevator car may be allowed to remain
stationary, or subsequently be moved, as required. The at least one
potential position may be calculated based on the time elapsed from
the point at which the actual position could not be determined.
[0009] It may be the case that it is only at a particular position,
or range of positions, within the elevator shaft that the position
reference system is not functioning properly. For example, this may
be due to the presence of dirt on part of the position reference
system. Therefore, by allowing the elevator car to move, the
position of the elevator car may once again be accurately
determined, when the elevator car moves to a position at which the
position reference system is functioning properly, e.g. where there
is no dirt impacting its functionality. Once the position of the
elevator car can again be determined from the position reference
system, the elevator system may continue to operate in a normal
manner, i.e. in which movement of the elevator car is controlled
based on its actual position. When the position cannot be
accurately determined, the elevator system may be configured to
generate a maintenance signal. Such a maintenance signal may
comprise a maintenance message. Such a message may, for example, be
sent to a service terminal of the elevator system such that
maintenance personnel are informed. Maintenance may then be
performed, e.g. by the clearing of dirt on the system, so that the
position can accurately be determined by the position reference
system.
[0010] Any suitable part of the elevator system may monitor the
position of the elevator car. For example, the controller may be
configured to monitor the position of the elevator car.
Accordingly, when the controller can no longer accurately determine
the position of the elevator car from the position reference
system, it may then calculate the potential position of the
elevator car as described above. Of course, other suitable means
may be provided, such as a separate dedicated controller, for
monitoring the position of the elevator car and suitably
controlling the system.
[0011] The at least one safety device may comprise any device which
is configured to indicate a potential hazard in the elevator
system. For example, the at least one safety device may comprise
any one of: emergency button stops, elevator car or landing door
sensors and/or limit switches. The safety devices may be physical
devices which are operable, e.g. by users of the system, or which
are triggered by parts of the system, e.g. the opening of doors.
Additionally, the safety devices may comprise virtual safety
devices, e.g. virtual limit switches. For example, the at least one
safety device may comprise a virtual upper limit switch, and a
virtual lower limit switch. Such virtual limit switches may
indicate that the elevator car is at the upper or lower limit of
the elevator shaft. Such switches may, for example, automatically
be triggered when the at least one potential position corresponds
to a position at which the virtual switches are associated with. In
other words, as soon as it is determined that a potential position
of the elevator car is at an uppermost limit, or a lowermost limit,
of the elevator shaft, the virtual upper or lower limit switch may
be triggered. As will be appreciated, with the system disclosed
herein, this will result in the stopping of the elevator car. The
elevator car may be arranged to move between a plurality of
landings within the elevator shaft.
[0012] Each of the at least one safety devices may be suitably
referenced, e.g. within the controller, such that the controller is
aware of the position of each safety device, or at least the
position at which the safety device indicates a potential hazard.
This may allow the controller to determine whether a triggered
safety device corresponds to one of the potential positions.
Additionally, each of the at least one safety devices may be
referenced such that the type and/or purpose of the safety device
is known by the controller. This information may be used by the
controller when controlling movement of the elevator car.
[0013] Calculation of the at least one potential position of the
elevator involves using an assumed motion profile of the elevator
car. The assumed motion profile may represent the expected motion
of the elevator car and may include any number of assumptions about
the movement of the elevator car which can be used in calculating
potential positions which the elevator car could at least
theoretically have moved to. The assumed motion profile may
comprise an elevator car speed component. The elevator car speed
component may vary depending on the time elapsed since loss of
actual position information. For example, the assumed motion
profile may include an elevator car speed which may initially
correspond to the speed at which the elevator car was moving prior
to loss of the positional information, and which may also change
based on the time elapsed since the loss of actual positional
information.
[0014] In a set of examples, the assumed motion profile comprises
an elevator car speed component which comprises a maximum possible
speed of the elevator car. This maximum speed may thus be used when
calculating the at least one potential position of the elevator
car. The elevator car speed may initially be less than the maximum
possible speed of the elevator car, but may follow an acceleration
profile which reaches the maximum speed. Using the maximum possible
elevator car speed and the time elapsed since the loss of position
information, it may be possible to calculate the maximum distance
the elevator car could have travelled. The elevator car may then,
theoretically, be anywhere between its original position and a
position corresponding to the maximum distance it could have
travelled. As will be appreciated, in using a maximum possible
speed, the assumed motion profile may thus work on `worst case
scenario` basis. The maximum possible speed for any given elevator
car may be known and/or determined in advance and thus be included
as part of the assumed motion profile. By assuming that the
elevator car is moving at the maximum possible speed, this may
contribute towards providing a maximum level of protection, as the
at least one position will correspond to the furthest position that
the elevator car could have moved to at in any given time. Of
course, the car speed which may form part of the assumed motion
profile may change depending on the time elapsed since the loss of
positional information.
[0015] With regard to the varying speed, the motion profile may
account for acceleration and deceleration of the elevator car. For
example, following loss of actual position information, it may be
assumed that the elevator car may accelerate up to a maximum speed,
after which it then travels at the maximum speed. During the
acceleration phase of such movement, the potential positions of the
elevator car may be calculated based on different speeds at each
time the potential speed is calculated at, taking into account the
potential acceleration of the elevator car. In a similar manner,
the elevator car may theoretically decelerate to a stop, at which
point its travel direction may reverse. Accordingly, the assumed
motion profile, and hence the calculated potential positions, may
also take into account the potential that the elevator car may have
to decelerate before it can move in an opposite direction. As such,
at least initially during the deceleration phase, the potential
positions may only be in the direction that the elevator car was
initially travelling. After the point at which the motion profile,
i.e. the deceleration component thereof, indicates that the
elevator car could have come to stop, potential positions in the
other direction may then be calculated.
[0016] The potential positions which the elevator car may be at may
also depend on the direction of movement of the elevator car at the
point at which its actual position was lost. Accordingly, in a set
of examples, the motion profile comprises an expected direction of
travel component of the elevator car. The expected direction of
travel component may comprise the direction at which the elevator
car was moving at the point of loss of actual positional
information, i.e. the expected direction of travel may correspond
to the initial direction of travel. For example, the assumed motion
profile may comprise an upward or downward direction of travel.
[0017] In addition or alternatively, it may comprise both an upward
and downward direction of travel such that potential positions in
both directions are calculated. The upward and downward components
of travel may contribute towards the calculation of the potential
positions at different points in time. For example, if the elevator
car was moving downward when its position was lost, the assumed
motion profile may comprise an expected direction of travel
component which indicates downward movement of the elevator car,
but after a certain period of time potential positions may also be
calculated in the upward direction to cover the scenario whereby
the direction of the elevator car has reversed. The at least one
potential position may then be calculated based on this and
potential positions below the last known position, at least
initially, may be calculated. Accounting for an expected direction
of travel, e.g. an initial direction of travel, may allow more
likely potential positions to be calculated, which may further
reduce the likelihood of nuisance events as potential positions in
a direction in which the elevator car is unlikely to be moving are
not calculated, and thus safety devices which trigger in the
opposite direction to which the elevator car is moving may not
cause the elevator car to be stopped. The expected direction of
travel component may vary based on the time elapsed since loss of
positional information and may also be dependent on an initial
speed of the elevator car at the point of loss of positional
information.
[0018] In examples in which the assumed motion profile comprises a
maximum possible speed, as discussed above, the maximum possible
speed may be different in an upward direction compared to a
downward direction. For example, the maximum possible speed in the
downward direction may be higher than the maximum possible speed in
the upward direction.
[0019] The assumed motion profile may be constant, i.e. it may
comprise a single speed and single direction. However,
alternatively, the motion profile may vary with time. For example,
the expected speed may increase, e.g. up to a maximum, over time,
and/or the expected travel direction may change over time. This may
therefore allow the controller to calculate potential positions
which more accurately reflect positions which the elevator car
could feasibly be at.
[0020] As discussed above, the controller uses the assumed motion
profile to calculate the at least one potential position of the
elevator car. In calculating the at least one potential position,
the controller may also use an initial reference position. The
initial reference position may correspond to the last known
position of the elevator car determined from the position reference
system. This reference position may thus provide a position which,
using the assumed motion profile, the at least one potential
position can be based on.
[0021] In a set of examples, the at least one potential position of
the elevator car comprises a plurality of potential positions. The
plurality of potential positions may correspond to a specific time.
For example, the controller may calculate a potential position in
an upward direction, as well as a potential position in a downward
direction, for any given time. In addition or alternatively, the
plurality of potential positions may be calculated at different
times so as to determine the potential positions as time elapses
from the loss of the actual position of the elevator car. The
controller may be configured to continuously determine the at least
one potential position of the elevator car. However, in a set of
examples, calculating the at least one potential position comprises
calculating the at least one potential position periodically. The
controller may, for example, be configured to calculate the at
least one potential position periodically at a set period, e.g.
every 5 ms or 100 ms or anywhere therebetween. Of course, any
period may be used, and the frequency at which the potential
positions are calculated may depend on the specific requirements of
the elevator system. For example, the frequency at which the
controller calculates the at least one potential position may
depend on the particular elevator system, for example the number
and position of the safety devices, and/or the potential speeds at
which the elevator car may move. Thus, as time elapses from the
point at which the actual position of the elevator car was lost,
the controller may periodically determine at least one potential
position of the elevator car. This may thus result in a plurality
of potential positions being calculated thus resulting in a range
of potential positions within the elevator shaft at which the
elevator car could be located. The potential positions may be
incrementally built up as time elapses, or they may be individually
calculated each time. This plurality of potential positions
calculated based on the elapsed time may take into account the fact
that the elevator car could continue to move in one direction, move
and stop, or even change direction completely.
[0022] For example, the elevator car may be at the 6.sup.th level
of a 20 level elevator shaft when the position of the elevator car
is lost. Following this loss, the elevator controller may
determine, e.g. after 2 seconds, that the potential positions of
the elevator car include the elevator being at the 5.sup.th level,
6.sup.th level or the 7.sup.th level. This may be based on the
assumed motion profile including an expected speed corresponding to
the elevator car moving one level every 2 seconds. Of course, the
elevator car may not have moved, hence the inclusion of the
6.sup.th level. After a further 2 seconds, if the actual position
of the elevator car is not recovered, the controller may calculate
that the elevator car could have travelled a further level and the
calculated potential positions may thus comprise the 4.sup.th,
5.sup.th, 6.sup.th, 7.sup.th or 8.sup.th levels. At any point, if a
safety device is triggered which corresponds to any one of these
levels, e.g. a safety device associated with the landing doors on
the 8.sup.th level, the controller may then stop movement of the
elevator car, irrespective of whether or not the elevator car is
actual at the level. Therefore, by calculating a plurality of
potential positions, e.g. periodically, maximum safety can be
ensured as any safety device corresponding to any of the plurality
of potential positions may cause the stopping of the elevator
car.
[0023] The potential positions calculated by the controller may
comprise a distance from a reference point, e.g. a pit, of the
elevator shaft. For example, it may be calculated that following a
position loss at 40 m from the pit of the elevator shaft, that the
elevator car could be at any position between 35 m from the pit of
the elevator shaft, through to 45 m from the pit of the elevator
shaft, after 5 seconds from the position loss assuming that the
elevator car travels at 1 m/s. Of course, the elevator car may
travel at higher speeds, e.g. at 5 m/s and thus in the same time
interval the elevator car could be at any position between 15 m
from the pit through the 65 m from the pit of the elevator shaft.
As discussed above, the assumed motion profile may include such
speed information and the potential positions may therefore be
calculated accordingly. With knowledge of the position of the
safety devices within the elevator system, or at least the positons
in the elevator shaft at which triggering of the sensor devices
represents a danger, the potential positions may then be used in
assessing whether a triggering of a sensor device requires stopping
of the elevator car.
[0024] However, in many elevator systems, safety devices are
typically associated with specific portions of the elevator shaft,
often those that correspond to elevator landings. Accordingly, it
may not be necessary to know a specific distance of the elevator
car from the elevator shaft. Therefore, in a set of examples, each
of the at least one potential position corresponds to at least one
positional zone within the elevator shaft. For example, the
positional zones may correspond to landings, i.e. levels, within
the elevator shaft. Each potential position may thus correspond,
for example, to a first, second, third landing etc. The positional
zones may also include the uppermost portion and lowermost portion
of the elevator shaft. At least some of the positional zones may
have corresponding safety devices. When a safety device at a
positional zone, or which indicates danger in a positional zone, is
triggered and the at least one potential position includes a
corresponding positional zone, the controller stops the elevator
car. The use of positional zones may be a particularly convenient
arrangement as many sensor devices within the elevator system may
be arranged at the landings, such as on the landing doors thereof
of as emergency stop at a landing.
[0025] In a set of examples, the position reference system
comprises an absolute position reference system configured to
provide an absolute position of the elevator car within the
elevator shaft. The absolute position reference system may comprise
any system which is capable, during normal operation, of providing
an absolute position of the elevator car within the elevator shaft.
It may, for example, comprise an optical or magnetic position
reference system arranged in the elevator shaft. For example, the
position reference system may an optical, e.g. camera-based,
readout system. Such a system may comprise a series of markings,
e.g. a code pattern, along the length of an elevator shaft, along
with a camera arranged on the elevator car and configured to read
the markings so as to enable determination of the absolute position
of the elevator car within the shaft.
[0026] In an alternative example, the position reference system
could comprise a magnetic-based system. Such a magnetic system may
comprise a magnetic coded tape that runs along the length of the
elevator shaft. The magnetic tape may be read, e.g. decoded, using
at least one, e.g. a plurality of, Hall sensor(s) arranged on the
elevator car, so as to determine the absolute position of the
elevator car within the elevator shaft. Of course, any other
suitable means may be used to enable determine the absolute
position of the elevator car within the elevator shaft. The
position reference system may also comprise an encoder arranged to
monitor movement of an elevator machine. The encoder may be
arranged to work in conjunction with the absolute position
reference system to provide an actual position of the elevator car
within the elevator shaft. The controller may be configured to
calculate the at least one potential position of the elevator car
when one or both of the absolute position reference system and
encoder fail to function properly.
[0027] In a set of examples, the at least one safety device
comprises a plurality of safety devices. Each of the plurality of
safety devices may correspond to a position, i.e. a potential
position, within the elevator shaft. Of course, more than one
safety device may correspond to a position with the elevator shaft.
In corresponding to a position, the safety device need not
necessarily be physically arranged at said position, but correspond
in a manner which means that triggering of the safety device is
indicative of a potential danger at said position.
[0028] The elevator system may comprise an elevator machine
configured to move the elevator car within the elevator shaft and a
brake configured to act on the elevator machine to stop the
elevator car from moving within the elevator shaft. The controller
may thus be configured to apply the brake to stop the elevator car
from moving within the elevator shaft.
[0029] According to another aspect of the present disclosure there
is provided a method of controlling the operation of an elevator
car within an elevator shaft comprising a plurality of safety
devices configured to indicate a hazard in the elevator system, the
method comprising: monitoring a position of the elevator car using
a position reference system; when an actual position of the
elevator car cannot be determined from the position reference
system, calculating at least one potential position of the elevator
car based on an assumed motion profile of the elevator car; and
allowing the elevator car to move when no safety device is
triggered which corresponds to the at least one potential position
of the elevator car, and stopping the elevator car from moving when
a safety device is triggered which corresponds to a potential
position of the elevator car.
[0030] In some examples of the method, the assumed motion profile
comprises an elevator car speed component comprising a maximum
possible speed of the elevator car.
[0031] In some examples of the method, the assumed motion profile
comprises a direction of movement component of the elevator
car.
[0032] In some examples of the method, calculating at least one
potential position of the elevator car also comprises using a last
known position of the elevator car within the elevator shaft.
[0033] In some examples of the method, calculating the at least one
potential position comprises calculating the at least one potential
position periodically.
[0034] In some examples of the method, calculating the at least one
potential position comprises calculating a plurality of potential
positions.
[0035] In some examples of the method, the at least one potential
position corresponds to positional zones within the elevator
shaft.
[0036] Advantages of the elevator system detailed above equally
apply to the method and associated examples set out herein.
Similarly, features of the elevator system described above may also
be applied to the method and associated examples set out above.
[0037] According to another aspect of the present disclosure there
is provided a computer program product comprising
computer-executable instructions, optionally embodied in a
non-transitory computer readable medium, which, when read by a
machine, cause the machine to perform the method according to any
one of the embodiments described above.
[0038] According to a further aspect of the present disclosure
there is provided a (non-transitory) computer readable medium
having the computer program product as described above stored
therein.
BRIEF DESCRIPTION OF THE DRAWINGS
[0039] Certain examples of the present disclosure will now be
described with reference to the accompanying drawings, in
which:
[0040] FIG. 1 is a schematic illustration of an elevator system
that may employ various embodiments of the present disclosure;
[0041] FIG. 2 is a schematic illustration of an elevator system in
accordance with an example of the present disclosure;
[0042] FIG. 3 is an illustration of a prior art elevator system for
comparison purposes;
[0043] FIG. 4 is an illustration of the elevator system shown in
FIG. 2 in operation when the actual position of the elevator car is
lost and when a landing door is opened whilst the position is
lost;
[0044] FIG. 5 is an illustration of the elevator system shown in
FIG. 2 when the actual position is lost whilst the elevator car is
stationary;
[0045] FIG. 6 is an illustration of the elevator system shown in
FIG. 2 when the actual position is lost whilst the elevator car is
moving upwards;
[0046] FIG. 7 is an illustration of the elevator system shown in
FIG. 2 when the actual position is lost whilst the elevator car is
initially moving upwards and subsequently changes to move
downwards;
[0047] FIG. 8 is an illustration of the elevator system shown in
FIG. 2 when the actual position is lost whilst the elevator car is
moving downwards; and
[0048] FIG. 9 is an illustration of the elevator system shown in
FIG. 2 when the actual position is lost whilst the elevator car is
initially moving downwards and subsequently changes to move
upwards.
DETAILED DESCRIPTION
[0049] FIG. 1 is a perspective view of an elevator system 101
including an elevator car 103, a counterweight 105, a tension
member 107, a guide rail 109, an elevator machine 111, an encoder
113, and a controller 115. The elevator car 103 and counterweight
105 are connected to each other by the tension member 107. The
tension member 107 may include or be configured as, for example,
ropes, steel cables, and/or coated-steel belts. The counterweight
105 is configured to balance a load of the elevator car 103 and is
configured to facilitate movement of the elevator car 103
concurrently and in an opposite direction with respect to the
counterweight 105 within an elevator shaft 117 and along the guide
rail 109.
[0050] The tension member 107 engages the elevator machine 111,
which is part of an overhead structure of the elevator system 101.
The elevator machine 111 is configured to control movement between
the elevator car 103 and the counterweight 105, and thus control
the position of the elevator car 103 within the elevator shaft 117.
The encoder 113 may be mounted on a fixed part at the top of the
elevator shaft 117, such as on a support or guide rail, and may be
configured to provide position signals related to a position of the
elevator car 103 within the elevator shaft 117. In other
embodiments, the encoder 113 may be directly mounted to a moving
component of the elevator machine 111, or may be located in other
positions and/or configurations as known in the art. The encoder
113 can be any device or mechanism for monitoring a position of an
elevator car and/or counterweight, as known in the art.
[0051] The controller 115 is located, as shown, in a controller
room 121 of the elevator shaft 117 and is configured to control the
operation of the elevator system 101, and particularly the elevator
car 103. For example, the controller 115 may provide drive signals
to the elevator machine 111 to control the acceleration,
deceleration, levelling, stopping, etc. of the elevator car 103.
The controller 115 may also be configured to receive position
signals from the encoder 113 or any other desired position
reference device. When moving up or down within the elevator shaft
117 along guide rail 109, the elevator car 103 may stop at one or
more landings 125 as controlled by the controller 115. Although
shown in a controller room 121, those of skill in the art will
appreciate that the controller 115 can be located and/or configured
in other locations or positions within the elevator system 101. In
one embodiment, the controller may be located remotely or in the
cloud.
[0052] The elevator machine 111 may include a motor or similar
driving mechanism. The elevator machine 111 may be configured to
include an electrically driven motor. The power supply for the
motor may be any power source, including a power grid, which, in
combination with other components, is supplied to the motor. The
elevator machine 111 may include a traction sheave that imparts
force to tension member 107 to move the elevator car 103 within
elevator shaft 117.
[0053] Although shown and described with a roping system including
a tension member 107, elevator systems that employ other methods
and mechanisms of moving an elevator car within an elevator shaft
may employ embodiments of the present disclosure. For example,
embodiments may be employed in ropeless elevator systems using a
linear motor to impart motion to an elevator car. Embodiments may
also be employed in ropeless elevator systems using a hydraulic
lift to impart motion to an elevator car. FIG. 1 is merely a
non-limiting example presented for illustrative and explanatory
purposes. Features of the elevator system 101 may be applied to the
elevator system described below.
[0054] FIG. 2 shows a schematic illustration of an elevator system
in accordance with the present disclosure. As shown, the elevator
system 201 comprises an elevator car 203 which is movable in an
elevator shaft 217 between a plurality of landings. The elevator
car 203 is coupled to a tension member 207 which is driven by an
elevator machine 211. The elevator machine 211 is thus configured
to move the elevator car 203, via the tension member 207, in the
elevator shaft 217.
[0055] A brake 208, in the form of a machine brake, is arranged to
act directly on the elevator machine 211 such that when the brake
208 is applied movement of the elevator machine 211 is stopped, and
consequently the elevator car 203 is stopped from moving within the
elevator shaft 217. Whilst the brake 208 illustrated is a machine
brake 208, any other form of brake that can suitably stop movement
of the elevator car 203 within the elevator shaft 217 may also be
used.
[0056] The elevator system 201 comprises a controller 215
configured to control movement of the elevator car 203. The
controller 215 is operatively connected to a drive 228 which in
turn is connected to the elevator machine 211 to control operation
of the elevator machine 211, and thus control movement of the
elevator car 203 within the elevator shaft 217. The drive 228 is a
separate controller which is configured to control the elevator
machine 211. An encoder 213 is arranged to measure the position and
speed of the elevator car 203, based on movement of the elevator
machine 211. The encoder 213 is operatively connected to the drive
228, which is coupled to the controller 215, thereby allowing the
controller 215 to suitably control the elevator machine 211 to
drive the elevator car 203 in the desired manner The encoder 213
may be used to determine the position, speed, acceleration,
deceleration of the elevator car 203, in conjunction with a
position reference system 234, as will be described in more detail
below.
[0057] A safety device 230 is operatively coupled to the controller
215. The safety device 230 may, for example, be connected to the
controller 215 via a wired or wireless connection. Whilst the
safety device 234 is illustrated as a single safety device 230, it
may comprise a plurality of safety devices. The safety device 230
may monitor a part of the elevator system, for example the opening
of a landing door. The safety device 230 may correspond to a
particular position, e.g. positional zone, within the elevator
shaft 217.
[0058] A further safety device 232 is part of the elevator car 203
and may function to monitor a status of the elevator car 203. For
example, the safety device 232 may be an emergency stop button
provided within the elevator car 203, a load sensor configured to
measure a load within the elevator car, or indeed any other
appropriate safety device. Similarly to the safety device 230
described above, the further safety device 232 is merely
illustrative, and any number of further safety devices 232 may be
provided. The further safety device 232 in the elevator car 203 may
be in communication with the controller 215 via any suitable means,
e.g. via a wired or wireless connection.
[0059] As discussed above in the summary section, the safety
devices 230, 232 may comprise any device which is capable of
monitoring the elevator system. For example, the safety devices
230, 232 may comprise at least one of: switches, load
[0060] sensors, speed sensors, emergency stop buttons or virtual
switches formed by a position reference system and associated
software etc.
[0061] Whilst not depicted, the safety devices 230, 232 may be
arranged as part of a safety chain, i.e. the safety devices 230,
232 may be operatively coupled either physically, or electronically
within the controller 215, such that the triggering of any one of
the safety devices 230, 232 causes the stopping of the elevator car
203. Similarly, resumption of service of the elevator car 203 may
require all of the safety devices 230, 232 within the safety chain
to be in a safe state. The safety devices 230, 232 may also be
suitably referenced so that the controller 215 can determine the
type, position and/or purpose of any given safety device 230, 232.
As discussed in detail in the summary section, this information may
be used when determining whether to allow the elevator car 203 to
move following the triggering of one of the safety devices 230,
232.
[0062] The elevator system 201 further comprises a position
reference system 234. The position reference system 234 may be an
absolute position reference system such that it is capable of
indicating the absolute position of the elevator car on its own, or
when coupled with the encoder 213. Parts of the position reference
system 234 may be distributed between the elevator car 203 and the
elevator shaft 217, as shown. For example, the position reference
system 234 may comprise a sensor, e.g. a camera or hall sensor(s),
arranged to read information from within the elevator shaft 217.
The position reference system 234 may comprise any suitable system
that is capable of determining a position, e.g. an absolute
position, of the elevator car 203 within the elevator shaft. The
position reference system 234 may be in communication with the
controller 215 in any suitable manner Through coupling of the
position reference system 234 and the controller 215, the
controller 215 thus has access to positional information 235 of the
elevator car 203.
[0063] In order to calculate the potential positions, in the event
of a loss of actual position of the elevator car 203, the
controller 215 may comprise an assumed motion profile 237 stored
therein. The assumed motion profile 237 may then be used, e.g. with
the last known position of the elevator car 203 obtained from the
position information 235, in order to calculate potential positions
of the elevator car 203. As depicted, the assumed motion profile
237 may comprise an expected speed 239 and an expected direction of
travel 241 component. The expected speed 239 may comprise a speed
profile which varies based on the time elapsed since the loss of
positional information. Additionally, the speed profile may also
depend on the initial direction of the elevator car 203. Similarly,
the expected direction of travel 241 component may also vary
depending on the time elapsed since loss of positional information
and may also vary based on the initial speed of the elevator car
203 when the actual positional information is lost. The assumed
motion profile 237 may be updated based on characteristics of the
elevator system 201, for example the direction of movement of the
elevator car 203 at a point at which its position is lost.
[0064] For comparison purposes, FIG. 3 shows the operation of a
prior art elevator system 301 operated in accordance with prior art
techniques. FIG. 3 shows a prior art elevator system 301 plotted at
two different points in time, t, with the position of the elevator
system's 301 components plotted against vertical position p, within
the elevator shaft 317. Illustrated components of the prior art
elevator system 301 include the elevator shaft 317, the elevator
car 303, inactive safety devices 330A, i.e. safety devices which
have not been triggered, as well as active safety devices 330B,
i.e. safety devices which are triggered and which cause the
stopping of the elevator car 303.
[0065] At time T1, the position of the elevator car 303 within the
elevator shaft 317 is known. However, at the time indicated by the
dashed line 340, the actual position of the elevator car 303 is
lost. Accordingly, as shown at time T2, despite the elevator car
303 being in the same position as time T1, the system 301 assumes
that the elevator car could be anywhere within the elevator shaft
317, as illustrated by the hatched marking throughout the entire
elevator shaft 317. This results in the immediate triggering of all
virtual position related safety devices within the elevator shaft
317. This may, for example, include the uppermost and lowermost
safety devices, as indicated by the uppermost and lowermost active
safety devices 330B.
[0066] Consequently, any further movement of the elevator car is
stopped. As is clearly visible in FIG. 3, the elevator car 303 is
at a significant distance from at least the lower active safety
device 330B and the upper active safety device 330B, and so there
is no need to stop the elevator car 203 so quickly. This therefore
results in a nuisance for users of the elevator system who are
trapped within the elevator car 303, or delayed access to the
elevator car 303, due to the unnecessary stopping of the elevator
car 303.
[0067] This is contrasted to the present invention which is
illustrated in the following Figures. FIGS. 4 to 9 each illustrate
a plot of the elevator system 201 including the elevator car 203,
within the elevator shaft 217, at six different points in time. The
elevator system 201 in each Figure is plotted at times T1, T2, T3,
T4, T5 and T6 on a graph of time, t, against position, p within the
elevator shaft 217. Only the elevator system 201 including the
elevator shaft 217, and associated components, at the first time T1
is labelled for clarity purposes. The elevator shaft 217 comprises
six landings 225, each with corresponding doors. Of course, this is
merely exemplary and the elevator system 201 may comprise any
number of landings 225.
[0068] Included on each Figure is a key illustrating key parts of
the plot. Features of the key are described below for completeness.
The square with a line therethrough is indicative of a closed door
242 and the blank square represents an open door 244. The elevator
system 201 also comprises a number of safety devices 230. The
safety devices 230 are illustrated in three different states. The
blank ellipses represent an active safety device 230A, i.e. a
safety device outputting a signal indicative of a potential hazard.
The solid ellipses, both horizontal and vertical, represent an
active and hazardous safety device 230B, i.e. a safety device which
outputs an active signal and which is also in a position which
corresponds to a potential position of the elevator car 203. The
blank rectangles, both vertical and horizontal, represent an
inactive safety device 230C, i.e. a safety device which is not
indicating a potential hazard. The solid continuous line 252 is
indicative of a point in time at which a loss of actual position of
the elevator car 203 occurs, and the dashed line 254 is indicative
of a point in time at which the elevator car's 203 actual position
is recovered. The hatched marking is indicative of the potential
positions 256 of the elevator car 203 when the actual position has
been lost, which may be calculated by the controller 215. In each
of the Figures, the illustrated position of the car 203 within the
elevator shaft 217 represents the actual position of the elevator
car 203 at any of the given times.
[0069] As depicted, each of the landings 225 comprises a door which
may be either a closed door 242 or an open door 240. Each of the
doors 225 may also comprise a corresponding safety device 230. When
the door is a closed door 242, the corresponding safety device 230
is an inactive safety device 230C. When the door is an open door
244, the safety device 230 may either be an active safety device
230A or an active and hazardous safety device 230B, depending on
the calculated potential positions 256. The safety devices 230
corresponding to the doors may be operatively coupled to the doors
themselves such that their state is determined by the position of
the doors. Additionally, there may be safety devices 230 at the
uppermost and lowermost portions of the elevator shaft 217. These
safety devices 230 in the uppermost and lowermost portions of the
elevator shaft may be virtual safety devices whose state is
determined by the position, or potential position, of the elevator
car 203 within the elevator shaft 217.
[0070] The potential positions 256 which are calculated in the
following examples may be considered to correspond to positional
zones within the elevator shaft 217, for example the potential
positions 256 may correspond to zones, e.g. landings 225, within
the elevator system 201. Alternatively, the potential positions 256
may instead be in the form of a distance from a reference point
within the elevator system 201 and thus the potential positions 256
may include any position within the elevator shaft 217, including
positions between different landings 225 and other regions within
the elevator shaft 217.
[0071] FIG. 4 illustrates the elevator system 201 and method in
accordance with the present disclosure. FIG. 4 shows a plot of the
elevator car 203 within the elevator shaft 217, at six different
points in time and wherein a safety device 230 is triggered during
the loss of actual positional information.
[0072] Operation of the elevator system 201 will now be described
with reference to FIG. 4, and with reference to the parts of the
elevator system 201 shown in FIG. 2. At time T1, the actual
position of the elevator car 203 is known, and none of the safety
devices 230 in the elevator shaft 217 are triggered, as illustrated
by the inactive safety devices 230C throughout the entire elevator
system 201. After time T1, the actual position of the elevator car
may be lost, e.g. due to the position reference system 234 and/or
the encoder 213 no longer being capable of providing an actual
position of the elevator car 203. The actual position of the
elevator car is 203 lost at the time indicated by the solid line
252. This loss of actual position may be detected by the controller
215 which may be configured to monitor the actual position of the
elevator car 203 using the position reference system 234.
[0073] The loss of positional information results in the controller
215, shown in FIG. 2, calculating potential positions 256 of the
elevator car 203. In the example shown in FIG. 4, the elevator car
203 was initially moving upward at the point of the position loss.
Accordingly, the controller 215 may use the last known position
from the positional information 235, along with the assumed motion
profile 237 to calculate at least one potential position of the
elevator car 203. In calculating this position, the controller 215
may use an expected direction of travel 241 of the elevator car 203
and an expected speed 239 which form part of the assumed motion
profile 237. The expected direction of travel 241 may include a
downward direction which indicates that at least for a certain
period of time the elevator car 203 will be travelling downward.
The potential positions 256 of the elevator car 203 may then be
calculated based on the time elapsed since the loss of positional
information.
[0074] As illustrated, at time T2, the controller 215 has
calculated a first potential position 256. This first potential
position 256 covers the second and third landings 225 and
encompasses the actual position of the elevator car 203. At time
T2, all of the safety devices 230 are inactive safety devices 230C,
i.e. none of the safety devices 230 have been triggered, and thus
the elevator car 203 is allowed to continue to move within the
elevator shaft 217.
[0075] As time passes from the point of position loss, the
controller 215 periodically calculates potential positions 256 of
the elevator car 203. The controller may, for example, calculate
the potential positions 256 periodically, e.g. once every 5 ms. At
time T3, the controller 215 again calculates further potential
positions 256 of the elevator car 203. As shown the potential
positions 256 of the elevator car 203 at time T3 include a larger
range of potential positions 256 within the elevator shaft 217.
Additionally, as depicted, at time T3 there is an open door 244. In
the example depicted, the open door 244 is on the fifth landing
225. This open door 244 results in an active safety device 230A on
the fifth landing 225. However, the active safety device 230A does
not correspond to the potential positions 248 calculated by the
controller 215, e.g. the active safety device 230A is not at a
position which corresponds to the potential positions 256 of the
elevator car 203, and thus the controller 215 allows the elevator
car 203 to continue moving.
[0076] At time T4, the potential positions 256 of the elevator car
203 are calculated again. As shown, these positions may be above or
below the actual position of the elevator car 203. This may be the
result of the assumed motion profile 237 which accounts for the
potential that by time T4, the elevator car 203 could be moving in
either direction. At time T5, the potential positions 256 of the
elevator car 203 are calculated again. As depicted, at this point,
the potential positions 256 encompass the safety device 230 on the
fifth landing which is now an active and hazardous safety device
230B. Accordingly, at time T5, the active and hazardous safety
device 230B, which is in a position which corresponds to a
potential position 256 of the elevator car 203, causes the elevator
car 203 to be stopped. This may be achieved by the application of
the machine brake 208 to the elevator machine 211.
[0077] As depicted, at time T5, the potential positions 256 also
encompass a safety device 230 which may be arranged in the pit of
the elevator shaft 217. The safety device 230 in the pit may be a
virtual safety device, e.g. in the form of a virtual limit switch.
Thus, when the potential positions 256 encompass the position of
the safety device 230 in the pit, the safety device 230 may also
become an active and hazardous safety device 230B which also
triggers the stopping of the elevator car 203. Accordingly, as
depicted, at time T5 the elevator car 203 is stationary. The
elevator car 203 may remain stationary until actual position
information of the elevator car 203 is available. As will be
appreciated, the elevator car 203 has moved a number of landings
225 since the initial loss of position, and thus any nuisance to
the users of the elevator system 201 may have been minimised.
[0078] The actual position of the elevator car 203 may be recovered
at the time indicated by the dashed line 254. This may, for
example, be due to the elevator car 203 having reached a position
within the elevator shaft 217 at which the position reference
system 234 is able to function properly. Additionally, this may
also be due to maintenance having been performed on the elevator
system 201, e.g. following cleaning of the position reference
system 234. The controller 215 may therefore release the brake 208
and allow the elevator car 203 to move again. As depicted at time
T6, following recovery of the elevator car's 203 position, as the
active safety device 230A is not adjacent the elevator car 203 or
indeed any potential position 256 of the elevator car 203, the
elevator car 203 is once again free to move within the elevator
shaft 217.
[0079] Of course, whilst the actual position of the elevator car
203 is depicted as being recovered at the time indicated by dashed
line 254, the position may instead be recovered earlier, e.g.
between times T3 and T4, after which the elevator system 201 may
then operate in a normal manner based on the actual position
information. Accordingly, the stopping of the elevator car at time
T5 may be avoided completely.
[0080] The above illustrates one exemplary case of the elevator
system 201 and method disclosed herein which utilises landing door
safety devices which are associated with landings 225 within the
elevator shaft 217. Of course, the principles described above may
equally apply to any other form of safety device arranged at any
suitable position in the elevator system 201. In the example shown,
the potential positions 256 may correspond to positional zones
which are associated with landings 225 within the elevator system
201. For example, the controller 215 may determine which landings
225, i.e. levels of the elevator system 201, the elevator car 203
could have potentially travelled to. However, in addition or
alternatively, the potential positions may comprise a distance from
a reference point within the elevator system 201, e.g. from a base
of the elevator shaft 217.
[0081] In the example described above, the assumed motion profile
237 may comprise an expected speed 239 which is equivalent to the
elevator car 203 moving at a maximum possible speed. Of course, any
other expected speed 239 may be used depending on the operational
parameters of the elevator system 201. Additionally, the assumed
motion profile 237 described above accounts for the likelihood that
the elevator car 203 will continue to move upwards, at least
initially, and may thus comprise a corresponding acceleration,
deceleration, speed or expected direction of movement profile which
accounts for such potential movement of the elevator car 203.
[0082] When compared to the prior art system as shown in FIG. 3,
the system 201 and method disclosed herein, and described above
with respect to FIG. 4, advantageously allows an elevator car 203
to continue to move even in the event of a loss of actual
positional information. The elevator system 201 is also nonetheless
capable of stopping the elevator car following the triggering of a
safety device which realistically represents a danger to the users.
Further, in allowing the elevator car 203 to continue to move, the
elevator system 201 may also recover its positional information,
thus permitting continued normal operation without requiring
further interaction, e.g. from maintenance personnel. The system
201 and method may, therefore, reduce the number of nuisance events
which are experienced by users of the system.
[0083] FIGS. 5 to 9 illustrate the calculation of potential
positions of the elevator car 203 with the elevator car 203 moving
in different directions within the elevator shaft 217. FIG. 5 shows
the exemplary case whereby the elevator car 203 is stationary when
the position of the elevator car 203 is lost. As illustrated, at
time T1, the position of the elevator car 203 is known. Following
the loss of positional information indicated by line 252, potential
positions 256 are then calculated by the controller 215 based on
the last known position from the positional information 235 and the
assumed motion profile 237. At time T2, the potential position 256
calculated encompass the actual position of the elevator car 203.
At time T3, the calculated potential positions not only include a
potential position encompassing the elevator car 203, but also a
potential position 248 at a level above and below the elevator car
203. Accordingly, when calculating the potential positions 256, the
controller 215 may utilise an assumed motion profile which may
include an expected direction of travel component which is in both
the upward and downward direction immediately following the loss of
positional information. This process is repeated at times T4 and T5
in which the number of potential positions 248 increases and thus
there is a greater range of positions in the elevator shaft 217
where the elevator car 203 could potentially be.
[0084] As illustrated, at time T5, the potential positions 256
includes the uppermost position within the elevator shaft 217. As a
result, a safety device 230 at the uppermost portion of the
elevator shaft 217 is triggered as indicated by the active and
hazardous safety device 230B at the top of the elevator shaft 217.
The safety device 230 at the top of the elevator shaft 217 may be a
virtual safety device, in the form of a virtual limit switch. As
the elevator car 203 is already stationary at this point, the
controller 215 may simply prevent the elevator car 203 from being
moved.
[0085] When the position of the elevator car 203 is recovered, i.e.
at the point in time indicated by the dashed line 254, the position
of the elevator car 203 is once again known at T6. As all of the
safety devices 230 are inactive safety devices 230C, the elevator
car 203 may be moved, e.g. in response to an elevator call, within
the elevator shaft 217.
[0086] FIG. 6 shows the exemplary case whereby the elevator car 203
is moving upwards when the position of the elevator car 203 is
lost. At time T1, the position of the elevator car is known. At the
point in time illustrated by the solid line 252, the position of
the elevator car 203 is lost. Accordingly, as the elevator car 203
was initially moving upwards, this information is used as part of
the assumed motion profile 237, specifically it forms part of the
expected travel direction 241 of the assumed motion profile 237.
Thus, the calculated potential position 256 at time T2 is above the
position of the elevator car 203 at time T1, because the
calculation of the potential position 256 assumes that the elevator
car 203 will continue to move upwards, at least initially. This
continues at time T3 at which it can be seen that the calculated
potential positions 256 include further positions in the upward
direction. At time T4, further potential positions 256 are
calculated. At this point in time, based on the assumed motion
profile 237, it may be the case that the elevator car 203 could
theoretically have continued to move upwards, but also that the
elevator car 203 could now have begun to move downward. In other
words, the assumed motion profile 237 may include both upward and
downward components of direction of travel at time T4. Accordingly,
as depicted, the calculated potential positions 256 now begin to
incorporate positions in a downward direction.
[0087] At time T5, as illustrated, the controller 215 has
calculated further potential positions 248 both in an upward and
downward direction. In all of the times from T2-T5, at least one of
the potential positions 248 corresponds to the actual position of
the elevator car 203, as illustrated. Accordingly, the calculated
potential positions 248 include the actual position of the elevator
car 203 thus meaning that any safety device 230 which is triggered
and corresponds to any of the calculated potential positions 256,
will cause the elevator car 203 to be stopped and thus ensure the
safety of the users of the elevator system 201. At time T5, the
potential positions 245 encompass a safety device 230 at the bottom
of the elevator shaft 217. This safety device 230 may be a virtual
limit switch arranged within the pit of the elevator shaft 217. As
depicted, the safety device 230 is thus an active and hazardous
safety device 230B which is within the potential positions 256 of
the elevator car 203. Accordingly, at this point, the elevator car
203 may be stopped, e.g. through application of the brake 208 to
the elevator machine 211.
[0088] At the point in time indicated by the dashed line 254, the
position of the elevator car 203 is recovered and at time T6 none
of the safety devices 230 are active, i.e. all the safety devices
230 in the elevator system 201 are inactive safety devices 230C,
and thus the elevator system 201 may then continue to operate in a
normal manner.
[0089] FIG. 7 shows the exemplary case whereby the elevator car 203
is initially moving upwards, at the point at which its position is
lost, but subsequently moves downwards whilst its actual position
is remains unknown. At time T1, the position of the elevator car
203 within the elevator shaft 217 is known. At the point in time
indicated by the solid line 252, the actual position of the
elevator car 203 can no longer be determined. Accordingly, at time
T2 the potential position 256 of the elevator car 203 is
calculated. This is achieved based on the last known position of
the elevator car 203, which corresponds to the position at time T1,
as well as an assumed motion profile 237 which includes an expected
travel direction 241 component. As depicted, the potential position
256 includes one level up from the known position at time T1.
Accordingly, at least at time T2, the assumed motion profile 237
incorporates the upward travel of the elevator car 203. Similarly,
at time T3, the potential positions 248 of the elevator car 203
include the level calculated at time T2, as well as the next level
up. However, as depicted, at time T3, the direction of travel of
the elevator car 203 reverses, and the elevator car 203 begins to
travel in a downward direction. This reversal of direction of the
elevator car 203 may be accounted for by the assumed motion profile
237 including an expected direction of travel component, which may
be in the form of a profile which varies with time. Accordingly, at
time T4, the calculated potential positions 256 now include further
potential positions 256 at levels above that calculated at time T3
and also potential positions 256 at levels below the position
calculated at T3, i.e. in the downward direction.
[0090] This process is further repeated at time T5 at which the
potential positions 256 now include a significant portion of the
elevator shaft 217. As depicted, at time T5, the potential
positions 256 encompass a safety device 230 which may be located in
the pit of the elevator shaft 217. The safety device 230 may be a
virtual limit switch, and due to the potential positions 256
encompassing the lowermost safety device 230, this safety device
230 may become an active and hazardous safety device 230B which
triggers stopping of the elevator car 203. Accordingly, at time T5,
the elevator car 203 may be stopped, e.g. through application of
the brake 208 to the elevator machine 211.
[0091] By taking into account the potential for the direction of
the elevator car 203 to change, the calculated potential positions
256 may include positions at which the elevator car 203 may have
moved to. As illustrated, despite the elevator car 203 changing
direction during its travel, the potential positons 256 nonetheless
includepotential positions 256 at which the elevator car 203 is
actually present. This ensures the safety of the users of the
elevator system 201.
[0092] As with previous examples, at the point in time illustrated
by dashed line 254 the actual position of the elevator car 203 is
recovered and thus the position of the elevator car 203 is once
again accurately known. The elevator system 201 may then continue
to operate in a normal manner.
[0093] FIG. 8 illustrates the exemplary case whereby the elevator
car 203 is moving downwards when the position is lost. In this
instance, the elevator system 201 operates in a similar manner to
that described above with respect to FIG. 6. However, unlike FIG. 6
in which the expected travel direction 241 is initially upwards, in
the example of FIG. 8 the expected travel direction 241, at least
initially, is downward. At time T1, the position of the elevator
car 203 is known. At the point in time indicated by the solid line
252 the actual position of the elevator car 203 is lost. Thus, at
time T2, a potential position 256 of the elevator car 203 is
calculated by the controller 215. As depicted, based on the
expected travel direction 241 being, at least initially, downward,
the potential position 256 is in a downward direction. At time T3,
further potential positions 256 of the elevator car 203 are
calculated. As depicted, the assumed motion profile 237 assumes
that the elevator car 203 will continue to be moving downwards at
this point in time, and thus further potential positions 256 in the
downward direction are calculated.
[0094] At time T4, further potential positions 256 are calculated.
At this point, the assumed motion profile 237 may account for the
possibility that the movement direction of the elevator car 203 may
have changed. Accordingly, at time T4 the calculated potential
positions 256 include potential positions 256 above and below the
potential positions 256 calculated at time T3, i.e. in both the
upward and downward directions. At time T5, further potential
positions 256 are calculated in a similar manner to that at time
T4, i.e. in both the upward and downward directions. As depicted,
the potential positions 256 of the elevator car 203 at time T5
include a potential position 256 of the elevator car 203 at the
uppermost portion of the elevator shaft 217.
[0095] The elevator shaft 217 may comprise a sensor device 230,
e.g. a virtual limit switch, at the top of the elevator shaft 217.
Thus, at time T5 in which the potential positions 256 include the
top of the elevator shaft 217, the sensor device 230 at the top of
the elevator shaft may become an active and hazardous sensor device
230B, which may cause the elevator car 203 to be stopped, e.g.
through application of the brake 208 to the elevator machine 211.
At the point in time indicated by dashed line 254, the actual
position of the elevator car 203 may be recovered, and thus at time
T6 the sensor device 230 at the top of the elevator shaft 217 is no
longer active, as indicated by the inactive sensor device 230C. The
elevator system 201 may then continue to operate in a normal
manner, e.g. by allowing the elevator car 203 to move freely within
the elevator shaft 217.
[0096] FIG. 9 illustrates the exemplary case whereby the elevator
car 203 is initially moving downwards, but reverses direction at a
point when its position is not accurately known. At time T1, the
position of the elevator car 203 is known. At the point in time
indicated by the solid line 252, the actual position of the
elevator car 203 is lost. Thus, at time T2, the controller 215
calculates a potential position 256 using the assumed motion
profile 237 and optionally the last known position of the elevator
car 203. At time T2, the calculated potential position 256 includes
potential positions in a downward direction, as the assumed motion
profile 237 may account for the fact that the elevator car 203 was
moving in the downward direction at the point of position loss. At
time T3, further potential positions 256 are calculated. As
depicted, these are also in the downward direction as the assumed
motion profile 237 may assume that the elevator car 203 is
continuing to move downward at this point. This may, for example,
be due to knowledge that it would take a certain distance or time
for the elevator car 203 to slow and reverse direction based on its
movement profile at the point of position loss at time T1.
[0097] Further, as with the exemplary case described above with
respect to FIG. 7, the assumed motion profile 237 may account for
the potential for the elevator car 203 to change its direction of
travel. Thus, at time T4, further potential positions 256 are
calculated which include potential positions 256 above and below
the potential positions 256 calculated at time T3. This therefore
accounts for the fact that the travel direction of the elevator car
203 may change.
[0098] At time T5, further potential positions 256 are calculated
on the same basis as at time T4. As depicted, at time T5 the
potential positions 256 may include the uppermost portion of the
elevator shaft 217. Similarly to the example described in FIG. 8,
the elevator system 201 may comprise a safety device 230, e.g. a
virtual limit switch, arranged at the top of the elevator shaft
217. Accordingly, when the potential positions 256 encompass this
uppermost position at which the elevator car 203 could be at, this
may cause the safety device 230 at the uppermost portion of the
elevator shaft 217 to become an active and hazardous safety device
230B, which causes the stopping of the elevator car 203. This
stopping may, for example, be achieved by the controller 215
causing the brake 208 to be applied to the elevator machine
211.
[0099] At the point in time indicated by the dashed line 254, the
actual position of the elevator car 203 is recovered. As the
elevator car 203 is not at the uppermost position in the elevator
shaft, at time T6, sensor devices 230 are all inactive safety
devices 230C. As discussed above with respect to earlier Figures,
at each of the times T2-T5 in the example of FIG. 9, there is
always a potential position 256 which corresponds to the actual
position of the elevator car 203. Thus the triggering of a safety
device 230 which corresponds to any one of these potential
positions 256 will cause the stopping of the elevator car 203 based
on the potential positions 256 of the elevator car 203, thereby
ensuring the safety of the users of the elevator system.
[0100] In the exemplary cases described above with reference to
FIGS. 5-9, the elevator system 201 allows the elevator car 203 to
continue moving, even following the loss of actual positional
information. This may therefore avoid nuisance events which may
improve the experience of users of the elevator system 201.
[0101] Additionally, in the examples described above, the assumed
motion profile 237 may also account for the potential that the
elevator car 203 may continue to move, at least by a small amount,
during the stopping of the elevator car. Accordingly, potential
positions of the elevator car 203 may continue to be calculated
until the elevator car has come to a complete stop. The assumed
motion profile 237 may include a braking profile which may be used
when calculating potential positions 256 following the stopping of
the elevator car 203. The braking profile may, for example, include
a deceleration component which indicates deceleration of the
elevator car 203.
[0102] The examples described above are merely intended to
illustrate the presen invention and may include a number of
modifications within the scope of the present invention. For
example, the assumed motion profile 237 may operate using any
suitable parameters. For example, the assumed motion profile 237
may always assume that the elevator car 203 can travel in either
direction. Alternatively, the assumed motion profile 237 may
account for the fact that the elevator car 203 may change
direction, and the point at which this occurs may vary depending on
a number of different factors including the type of elevator
installation, the motion of the elevator car 203 at the point at
which its position is lost, along with other suitable factors. For
example, if the elevator car 203 was moving slowly as at the point
of position loss, the assumed motion profile 237 may work on the
basis that the elevator car 203 may change direction in a shorter
distance or shorter time. Similarly, if the elevator car 203 was
moving quickly at the point of position loss, the time or distance
at which the elevator car 203 may change direction may be
increased. The assumed motion profile 237 may also take into
account acceleration and deceleration profiles of the elevator car
203 which may be different between different elevator installations
and/or the movement of the elevator car 203 at the point of
positional loss.
[0103] Accordingly, it will be appreciated by those skilled in the
art that examples of the present disclosure provide an improved
elevator system and method which is capable of continuing operation
even when an actual position of the elevator car of the elevator
system is not known. While specific examples of the disclosure have
been described in detail, it will be appreciated by those skilled
in the art that the examples described in detail are not limiting
on the scope of the disclosure.
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